The present invention relates generally to thermally expansible structural reinforcing members used to provide localized stiffness to frames, cavities, panels or other structural members, and more particularly to a reinforcing member including a base and a series of laterally extending arms each having a portion of thermally expansible reinforcing material secured thereto.
The design of automobiles, aircraft, watercraft and other common vehicles incorporate body structures having hollow cavities and open frame sections. The hollow cavities are commonly formed when it is desired to have an inner and outer wall defining a preferred structural or aesthetic characteristic. It is common for such structures to experience linear and rotational forces generated from environmental inputs associated with a given common vehicle. Such forces may encourage unwanted noise or premature fatigue failure in the structure.
It is frequently desirable to reinforce these areas for purposes of improving the structural integrity of the body. Increased stiffness in localized critical areas generally result in reduced vibration, noise, and/or fatigue propagation. Additionally, an increased stiffness in these areas generally has proven to improve energy management during crash or impact situations.
It is known to reinforce such areas by introducing self-sustaining reinforcing products into the cavity. The reinforcing products may include a support or carrier structure used to hold the material in the desired location. While this known technique has generally proven to provide increased stiffness, it adds access weight to the structural member.
Another known technique incorporates the use of a thermally expandable reinforcing material. The reinforcing material is positioned in a cavity and is heated during thermal convection activation process. The material is configured to expand and contact the surrounding cavity walls during a bake process. Often, however, the expandable material is disposed or arranged on a carrier or frame such that effective thermal exposure is difficult. Failure to fully penetrate the expandable material with heat results in inconsistent material density after expansion. It is therefore desirable to provide a frame and expandable material configuration such that the thermal activation process enables full heat penetration throughout the structure, thereby yielding a more consistent reinforcing structure.
It is a general object of the present invention to provide a reinforcing support having a rigid frame including a first and second laterally displaced shelf members, the shelf members carrying thermally expandable material thereon.
In one form, the present invention provides a reinforced structural member having a frame including a first mounting portion and first and second shelf members laterally extending therefrom. A thermally expandable reinforcing material is carried by each shelf member. The arms are preferably configured such that a gap is realized between the reinforcing material of a first shelf member and an adjacent shelf member prior to expansion.
The configuration of the frame increases the heat transfer to the core of the material where it is needed most. The gaps provided allow the shelf members of the frame to absorb and transfer heat more efficiently to the reinforcing material. Additionally, the shelved frame provides support for the reinforcing material to reduce the potential of material sag due to gravity during the expanding and curing process.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.